Parallel.Foreach maintain collection order?

Question

Is there a way to guarantee order when using Parallel.ForEach()? The collection I am looping over needs to maintain it's order but I was looking for some performance improvement.

Answer 1

In order to retain the order you must try to order the list before passing it to foreach loop since by default the Parallel.Foreach treats the list as unordered.

Example :

Parallel.ForEach(
list.AsParallel().AsOrdered(), 
(listItems) => {<operations that you need to do>});